What is T8 Lighting

T8 lighting is a type of fluorescent lighting. The first fluorescent lamps were introduced as commercial products in 1939. 32 Watt, T8 lighting was introduced in 1981 and this type of lighting was a significant improvement over older styles. When we talk about “T8” lighting the “T” refers to the shape of the lamp which is a tubular shape. The number following the T, in this case “8”, refers to the diameter of the lamp measured in eighths of an inch. So, a T8 lamp is a tubular lamp that measures 1 inch in diameter (8/8 inch).

Improvements Over Older Styles

T8 lighting remains a bright longer than the older, T12 style lamps. As time passes all lamps will start to lose brightness and intensity but T8 lighting loses its brightness and intensity at a slower rate than T12 lamps. T8 lamps will lose about 10% of their initial brightness after 7000 hours of use while T12 lamps can lose as much as 20% of their initial brightness in the same time period.

T8 lamps also have improved color characteristics. The color characteristics of a fluorescent lamp are primarily determined by their phosphor coating. T12 lamps use halophosphates to achieve their desired color. T8 lamps coat the inside of the tube with halophosphates as well but then also coat the inside of the tubes with a blend of rare earth phosphors which gives improved color rendering and higher efficacy.

How Long Will T8 Lighting Last?

T8 lamps have a 20,000 hour rated lamp life. The way lamp life ratings are determined is by measuring a large sample size of lamps and cycling them on for 3 hours and off for 20 minutes. The number of hours it takes for half of the lamps to burn out is the number reported as the average lamp life. Because T8 lamps have a 20,000 hour lamp life, this means that approximately half of the lamps will burn out before 20,000 hours of use and half will last longer than 20,000 hours.

It is also important to note that the way the lighting is used will have an effect on its life expectancy. Lamps with a longer burn cycle will have a longer average lifespan. For example, if the lamps are used in an office where they are left on all day or in a warehouse where they are left on for 24 hours per day, the lifespan of the lamps can increase considerably. T8 lighting that is left on for 24 hours per day may have an average life of up to 38,000 hours. On the other hand, if the lamps are constantly turned on and off they will have a much shorter lifespan. It is important to note however that although turning lights on and off repeatedly reduces their lifespan it is usually more economical to turn the lights off when they are not being used because it is far more energy-efficient.